Move soil_tifeedback into a module waterice_tifeedback_mod.F90
The flag to call tifeedback has been changed from "tifeedback" to surfaceice_tifeedback for clarity
Add the possibility to change the thermal inertia while pore ices is forming in the soil: to do so, use the flag poreice_tifeedback. The computation is done in waterice_tifeedback_mod.F90.
For now, surfaceice_tifeedback and poreice_tifeedback can not be called together, we might think about how to merge later.
LL